Gliederung

Objectives: Respiratory infection and failure is a common problem in intensive care unit (ICU) patients. However, despite the accumulating body of evidence to suggest that herpes simplex virus (HSV) is associated with pneumonia, this virus' exact role in this process is still not fully understood. Therefore, to identify patients at risk, we conducted a case control study to characterize patients with HSV-positive pneumonia.

Patients and methods:Between 2007 and 2009, all patients with suspected viral pneumonia (N=191) were tested for the presence of herpesviruses using a PCR approach with respiratory specimens. To identify possible associations, risk factors, and impact of HSV, HSV-positive patients (N=51) were compared to age-, gender-, and department- and season-matched HSV negative patients (N=52).

Results: HSV-positive patients differed significantly from the HSV-negative ones only with regard to time of mechanical ventilation (13 days in the HSV-positive group versus 6 days in the HSV-negative group; p=0.002). Subgroup analysis in the patients aged >60 years and in those without bacterial detection revealed a similar trend (p=0.01; p=0.004). Mortality did not differ between both groups or between the HSV-positive patients treated with aciclovir and HSV-positive patients who were not. A high viral load (>10E+05 geq/ml) was associated with mechanical ventilation (20/21 vs. 17/29; p=0.004), ARDS (19/21 vs. 18/29; p=0.005), sepsis (18/21 vs. 14/29; p=0.008), detection of a bacterial pathogen in the same specimen (10/21 vs. 4/29; p=0.01), and longer ICU stay (25 vs. 30 days; p=0.04).

Conclusions: Despite several associations with high viral load, the clinical outcome of HSV-positive patients did not differ significantly from the clinical outcome of HSV-negative patients. This finding may indicate that HSV viral loads in respiratory specimens are rather a symptom of clinically poor condition than a cause of it. Longitudinal and therapy studies are therefore needed to distinguish between HSV as a causative pathogen and HSV as a bystander of pneumonia / ARDS.